Semiconductor device and method for manufacturing the same

ABSTRACT

There is formed a first concave portion that extends inside a semiconductor substrate from a main surface thereof. An insulating film is formed over the main surface, over a side wall and a bottom wall of the first concave portion so as to cover an element and to form a capped hollow in the first concave portion. A first hole portion is formed in the insulating film so as to reach the hollow in the first concave portion from an upper surface of the insulating film, and to reach the semiconductor substrate on the bottom wall of the first concave portion while leaving the insulating film over the side wall of the first concave portion. There is formed a second hole portion that reaches the conductive portion from the upper surface of the insulating film. The first and second hole portions are formed by the same etching treatment.

CROSS-REFERENCE TO RELATED APPLICATION

The disclosure of Japanese Patent Application No. 2013-167690 filed onAug. 12, 2013 including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND

The present invention relates to a semiconductor device and a method formanufacturing the same, and in particular, to a semiconductor devicehaving a concave portion and a method for manufacturing the same.

DESCRIPTION OF THE RELATED ART

On one (upper-side) main surface side of a pair of main surfaces of asemiconductor substrate, which face each other, may be formed a deepgroove (concave portion) for taking out a potential of the other(lower-side) main surface side of the above-described pair of mainsurfaces. Such a deep concave portion for extracting the potential ofthe semiconductor substrate may be referred to as a substrate electrodeor a substrate contact. The above-described substrate electrode isdisclosed in, for example, Japanese Patent Laid-Open No. 2008-130829(Patent Document 1), National Publication of International PatentApplication No. 2008-511981 (Patent Document 2), Japanese PatentLaid-Open No. 05-29603 (Patent Document 3), Japanese Patent Laid-OpenNo. 62-213121 (Patent Document 4), and Japanese Patent Laid-Open No.2003-218356 (Patent Document 5).

Furthermore, in, for example, Japanese Patent Laid-Open No. 11-45890(Patent Document 6), disclosed is a technology to form a deviceisolation concave portion as a deep concave portion in one (upper-side)main surface of a pair of main surfaces of a semiconductor substrate forthe purpose of electrically separating elements formed over thesemiconductor substrate from the other region over the semiconductorsubstrate.

Prolonged heat treatment is needed in many cases, and manufacturing costmay be raised, in order to form the deep concave portion as shown in theabove-described Patent Documents.

In addition, in addition to the process of forming the above-describeddeep concave portion in forming a semiconductor device, there may beusually needed, for example, a process of forming a concave portion forpulling out an electrode from the semiconductor device, the concaveportion being shallower than the above-described deep concave portion,on the above-described one main surface side of the semiconductorsubstrate. The process of forming the deep concave portion and theprocess of forming the shallow concave portion are processed as separateprocesses in all the above-described Patent Documents. In this case,since processes become complicated, and the number of masks needed forforming the concave portion increases, manufacturing cost may be raised.

The other purposes and the new feature will become clear from thedescription of the present specification and the accompanying drawings.

SUMMARY

A method for manufacturing a semiconductor device of one embodimentincludes the following processes. First, there is formed an element thathas a conductive portion located at a main surface of a semiconductorsubstrate. There is formed a first concave portion that extends insidethe semiconductor substrate from the above-described main surface. Aninsulating film is formed over the main surface, over a side wall and abottom wall of the first concave portion so as to cover theabove-described element, and to form a capped hollow in the firstconcave portion. A first hole portion is formed in the insulating filmso as to reach the hollow in the first concave portion from an uppersurface of the above-described insulating film, and to reach thesemiconductor substrate on the bottom wall of the first concave portionwhile leaving the insulating film over the side wall of the firstconcave portion. There is formed a second hole portion that reaches theconductive portion from the upper surface of the above-describedinsulating film. The above-described first and second hole portions areformed by the same etching treatment.

A semiconductor device of the other embodiment includes the followingconfiguration. The above-described semiconductor device includes: asemiconductor substrate that has a first concave portion; an elementthat has a conductive region; and an insulating film that is formed overa main surface so as to cover the element, and is formed so as to exposea semiconductor substrate on a first bottom wall of the first concaveportion. There is formed a first hole portion that reaches the bottomwall of the first concave portion through an inside of the first concaveportion from an upper surface of the insulating film, and there isformed a second hole portion that reaches the conductive region from theupper surface of the insulating film. The semiconductor device includes:a first conductive layer formed in the first hole portion; and a secondconductive layer formed in the second hole portion. The first conductivelayer and the second conductive layer include the same material.

According to the semiconductor device and the method for manufacturingthe same pertaining to one embodiment and the other embodiment, thesemiconductor device having the first concave portion can be provided byreduction in the number of processes, a treatment time, andmanufacturing cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan diagram showing a configuration of asemiconductor device in a chip state in a First Embodiment;

FIG. 2 is a partially broken perspective diagram showing that theelement formation region shown in FIG. 1 has been surrounded by aconcave portion in a plan view;

FIG. 3 is a schematic cross-sectional diagram in a portion along a lineIII-III of FIG. 1 showing the configuration of the semiconductor devicein the chip state in the First Embodiment;

FIG. 4 is a schematic cross-sectional diagram showing in detail aspectsof an element or the like formed in each region of FIG. 3;

FIG. 5 is a schematic cross-sectional diagram showing a first process ofa method for manufacturing the semiconductor device in the FirstEmbodiment;

FIG. 6 is a schematic cross-sectional diagram showing a second processof the method for manufacturing the semiconductor device in the FirstEmbodiment;

FIG. 7 is a schematic cross-sectional diagram showing a third process ofthe method for manufacturing the semiconductor device in the FirstEmbodiment;

FIG. 8 is a schematic cross-sectional diagram showing a fourth processof the method for manufacturing the semiconductor device in the FirstEmbodiment;

FIG. 9 is a schematic cross-sectional diagram showing a fifth process ofthe method for manufacturing the semiconductor device in the FirstEmbodiment;

FIG. 10 is a schematic cross-sectional diagram showing a sixth processof the method for manufacturing the semiconductor device in the FirstEmbodiment;

FIG. 11 is a schematic cross-sectional diagram showing a seventh processof the method for manufacturing the semiconductor device in the FirstEmbodiment;

FIG. 12 is a schematic cross-sectional diagram showing an eighth processof the method for manufacturing the semiconductor device in the FirstEmbodiment;

FIG. 13 is a schematic cross-sectional diagram showing a ninth processof the method for manufacturing the semiconductor device in the FirstEmbodiment;

FIG. 14 is a schematic cross-sectional diagram showing a tenth processof the method for manufacturing the semiconductor device in the FirstEmbodiment;

FIG. 15 is a schematic cross-sectional diagram showing an eleventhprocess of the method for manufacturing the semiconductor device in theFirst Embodiment;

FIG. 16 is a schematic cross-sectional diagram showing a twelfth processof the method for manufacturing the semiconductor device in the FirstEmbodiment;

FIG. 17 is a schematic cross-sectional diagram in the portion along theline of FIG. 1 showing a configuration of a semiconductor device in achip state in a comparative example of the First Embodiment;

FIG. 18A is a schematic perspective diagram showing a configuration anda size of a substrate contact in the First Embodiment, and FIG. 18B is aschematic perspective diagram showing a configuration and a size of asubstrate contact in the comparative example;

FIG. 19 is a schematic cross-sectional diagram in a portion similar tothe portion along the line of FIG. 1 showing a configuration of asemiconductor device in a chip state in a Second Embodiment;

FIG. 20 is a schematic cross-sectional diagram in a portion similar tothe portion along the line of FIG. 1 showing a configuration of asemiconductor device in a chip state in a comparative example of theSecond Embodiment;

FIG. 21 is a schematic cross-sectional diagram in a portion similar tothe portion along the line of FIG. 1 showing a configuration of asemiconductor device in a chip state in a Third Embodiment;

FIG. 22 is a schematic cross-sectional diagram in a portion similar tothe portion along the line of FIG. 1 showing a configuration of asemiconductor device in a chip state in a comparative example of theThird Embodiment;

FIG. 23 is a schematic plan diagram showing a configuration of asemiconductor device in a chip state in a Fourth Embodiment;

FIG. 24 is a schematic cross-sectional diagram in a portion along a lineXXIV-XXIV of FIG. 23 showing the configuration of the semiconductordevice in the chip state in the Fourth Embodiment; and

FIG. 25 is a schematic cross-sectional diagram showing in detail aspectsof an element or the like formed in each region of FIG. 24.

DETAILED DESCRIPTION

Hereinafter, one embodiment will be explained on the basis of drawings.

First Embodiment

First, using FIGS. 1 and 2, there will be explained arrangement of eachelement formation region on a main surface of a semiconductor substrateof a semiconductor device of the present embodiment.

Referring to FIG. 1, the semiconductor device of the present embodiment,for example, has: a logic portion LG as a CMOS (Complementary MOS)transistor region in which a low-voltage CMOS transistor has beenintegrated; and an output driver portion HV as a high-voltage MOStransistor region using a high-voltage element, on a main surface of asemiconductor substrate SUB included in a semiconductor chip CHP. In theabove-described semiconductor device, as one example, one logic portionLG and three output driver portions HV are arranged so as to be a matrixform in a plan view.

A substrate electrode region is arranged outside a region where thelogic portion LG and the output driver portions HV are arranged (forexample, a region comparatively near an outer edge of the semiconductorchip CHP), and substrate contacts SCN are formed in the substrateelectrode region. However, positions at which the substrate contacts SCNare formed are not limited to an outer edge side of the semiconductorchip CHP, and they can be set as arbitrary positions. For example, thesubstrate contacts SCN may be formed in a center of the semiconductorchip CHP.

Referring to FIGS. 1 and 2, an element formation region DFR as the logicportion LG or the output driver portion HV is surrounded in a plan viewby an element isolation region DTR as a so-called DTI (Deep TrenchIsolation) structure having an insulating film in a concave portion witha high aspect ratio. The element isolation region DTR is formed on themain surface of semiconductor substrate SUB.

Next, a cross-sectional configuration of the above-describedsemiconductor device will be explained using FIG. 3.

Referring to FIG. 3, the semiconductor substrate SUB has, for example, aconfiguration in which a p-type impurity region PSB, a p-type epitaxiallayer PE1, an n-type buried layer NBL, and a p-type epitaxial layer PE2have been stacked in this order.

The p-type impurity region PSB is a substrate region (as a p⁺ region)having a comparatively high impurity concentration of a p-type (firstconductive type), and is formed in a region (lowermost region of thesemiconductor substrate SUB of FIG. 3) farthest from the main surface ofthe semiconductor substrate SUB on which the CMOS transistor and thelike are formed.

The n-type buried layer NBL (a buried region) is a n-type impurityregion formed so as to be located at a side (an upper side in FIG. 3)closer to the main surface on which the CMOS transistor and the like areformed than the p-type impurity region PSB in the semiconductorsubstrate SUB, the n-type impurity region having a medium n-type (secondconductive-type) impurity concentration. The p-type epitaxial layers PE1and PE2 are p⁻ regions of having comparatively low p-type impurityconcentrations.

These respective layers constituting the semiconductor substrate SUB areall formed as semiconductor regions containing an n-type or a p-typeconductive impurity. Meanwhile, the above-described respective regions(the p-type impurity region PSB, the p-type epitaxial layer PE1, then-type buried layer NBL, and the p-type epitaxial layer PE2) are formedon an entire surface of the semiconductor substrate SUB in a plan view.However, the entire surface here means an entire region in a plan viewof the semiconductor substrate SUB excluding a region where the elementisolation region DTR, the substrate contact SCN, and the like areformed.

Both of an n-type transistor and a p-type transistor may be formed inthe CMOS transistor region as the logic portion LG, and the high-voltageMOS transistor region as the output driver portion HV. For this reason,as shown in FIG. 3, a high-voltage n-type well region HNW may be formedin a region where the p-type epitaxial layer PE2 is formed, or forexample, a p-type well region, which is not shown, may be formed insteadof the high-voltage n-type well region HNW. Alternatively, both of then-type well region and the p-type well region may be formed.

The element isolation region DTR that surrounds the CMOS transistorregion as the logic portion LG and the high-voltage MOS transistorregion as the output driver portion HV has a configuration in which aninsulating film II1 and a hollow AG have been formed inside a concaveportion TI. Specifically, the concave portion TI is formed so as toextend inside the semiconductor substrate SUB from the main surface(main surface on a side opposite to a main surface in contact with then-type buried layer NBL of the p-type epitaxial layer PE2) of thesemiconductor substrate SUB, and to extend in a direction (directionwhere the epitaxial layer PE1 and the like are stacked) vertical to themain surface of the semiconductor substrate SUB. The insulating film II1is formed on a side wall and a bottom wall of the concave portion TI,and the hollow AG as a void (bubble) in which the insulating film II1 isnot arranged is formed in a region surrounded by the insulating film II1in the concave portion TI.

The substrate contact SCN of the substrate electrode region has aconfiguration in which the insulating film II1 and the substrate contactconductive layer CDL have been formed inside the concave portion TI.Specifically, the insulating film II1 is formed over the side wall ofthe concave portion TI, and the region surrounded by the insulating filmII1 in the concave portion TI is filled with the substrate contactconductive layer CDL. The substrate contact conductive layer CDL extendsalong a direction where the concave portion TI extends, and is formed soas to reach the bottom wall of the concave portion TI.

The insulating film II1 is formed so as to cover an upper surface of theinterlayer insulating film II that covers a region other than a regionwhere the element isolation region DTR, the substrate contact SCN, and aplug conductive layer PL1 (in the CMOS transistor region, and the like)are formed, in the main surface of the semiconductor substrate SUB(p-type epitaxial layer PE2). This insulating film II1 is formed so asto continue from a region over the upper surface of the interlayerinsulating film II even to an inside of the concave portion TI. Here,the inside of the concave portion TI means portions over the side walland the bottom wall of the concave portion TI constituting the elementisolation region DTR, and the side wall of the concave portion TIconstituting the substrate contact SCN.

Inside the semiconductor substrate SUB, the concave portions TI of theelement isolation region DTR and the substrate contact SCN are formed soas to penetrate through the p-type epitaxial layer PE2, the n-typeburied layer NBL, and the p-type epitaxial layer PE1 and to reach aninside of the p-type impurity region PSB, from one main surface of thep-type epitaxial layer PE2. However, the concave portion TI is notlimited to such an aspect, and, for example, it may have an aspect ofpenetrating through the p-type epitaxial layer PE2, the n-type buriedlayer NBL, and the p-type epitaxial layer PE1 to thereby extend anlowermost part of the p-type epitaxial layer PE1 (so as not enter theinside of the p-type impurity region PSB). However, the concave portionTI is preferably formed so as to penetrate through the n-type buriedlayer NBL to reach the p-type impurity region PSB.

Meanwhile, as will be mentioned later, a wiring layer ICL1 is formed soas to cover the substrate contact conductive layer CDL of the substratecontact SON and the plug conductive layer PL1, and to be electricallycoupled to these.

Next, by using FIG. 4, configurations of the CMOS transistor region andthe high-voltage MOS transistor region of FIG. 3 will be explained inmore detail.

Referring to FIG. 4, the semiconductor substrate SUB included in thesemiconductor chip CHP is formed by: the p-type impurity region PSB; thep-type epitaxial layer PE1; the n-type buried layer NBL; and the p-typeepitaxial layer PE2 (as described above), and these are allsemiconductor region containing a conductive impurity. Namely, thesemiconductor substrate SUB includes only the semiconductor regions.

Here, the semiconductor substrate SUB “including only the semiconductorregions” means a bulk semiconductor substrate, and a substrate such asan SOI (Silicon on Insulator) substrate in which an insulating film issandwiched therebetween, is not included. However, a device isolationinsulating film such as LOCOS (Local Oxidation of Silicon) and STI(Shallow Trench Isolation) may be formed on this “semiconductorsubstrate”.

Accordingly, the concave portions TI of the element isolation region DTRand the like are formed without penetrating through a region having aninsulating property. However, as will be mentioned later, thesemiconductor substrate SUB may further include a p-type buried layer.

For example, a CMOS transistor is formed in a CMOS transistor region,and this CMOS transistor has a configuration in which an NMOS transistoron a left side and a PMOS transistor on a right side in FIG. 4 have beencombined with each other. Namely, the CMOS transistor region has an NMOSregion where the NMOS transistor is formed, and a PMOS region where thePMOS transistor is formed, and the NMOS transistor is formed in the NMOSregion and the PMOS transistor is formed in the PMOS region,respectively. Meanwhile, here, among CMOS transistors used as logiccircuits, the NMOS transistor and the PMOS transistor which are used asan input/output circuit (I/O circuit) electrically coupled to the othersemiconductor device are shown as one example.

The NMOS transistor mainly has: a p-type well region PWR formed at thep-type epitaxial layer PE2; an n⁺ region NR (a conductive region) as asource region or a drain region; a gate insulating film GI; a gateelectrode layer GE; and a side wall insulating film SW. The PMOStransistor mainly has: an n-type well region NWR formed at the p-typeepitaxial layer PE2; a p⁺ region PR (conductive region) as the sourceregion or the drain region; the gate insulating film GI; the gateelectrode layer GE; and the side wall insulating film SW.

In the high-voltage MOS transistor region, there is formed ahigh-voltage MOS transistor that can withstand the use under ahigh-voltage. This high-voltage MOS transistor mainly has: the n-typewell region NWR; an n-type offset region NOR; the p-type well regionPWR; the n⁺ region NR and the p⁺ region PR (conductive regions) as thesource region or the drain region; the gate insulating film GI; the gateelectrode layer GE; and the side wall insulating film SW. As describedabove, elements such as the NMOS transistor are formed so as to have aconductive region at the main surface of the semiconductor substrateSUB.

Meanwhile, although, in FIG. 4, the p-type well region PWR and then-type well region NWR which constitute the CMOS transistor and thehigh-voltage MOS transistor are formed at the p-type epitaxial layerPE2, they may be formed at the high-voltage n-type well region HNW shownin FIG. 3. In addition, although in the present embodiment, a cobaltsilicide layer SC is preferably formed over the respective surfaces ofthe n⁺ region NR, the p⁺ region PR, and the gate electrode layer GE, thecobalt silicide layer SC may be omitted. Furthermore, although it ispreferable that a nitride film NF is further formed over the cobaltsilicide layer SC of the gate electrode layer GE, or the like, thisnitride film NF may also be omitted.

In order to electrically separate a set of the NMOS transistor and thePMOS transistor as the CMOS transistor formed in the CMOS transistorregion of FIG. 4, a buried insulating film BIL is formed on the mainsurface of the semiconductor substrate SUB between the NMOS transistorand the PMOS transistor. The buried insulating film BIL has aconfiguration in which the inside of the concave portion selectivelyformed in the main surface of the semiconductor substrate SUB has beenfilled with the insulating film (for example, a silicon oxidation film).

A similar buried insulating film BIL is formed also in some regions ofthe high-voltage MOS transistor. In addition, the element isolationregion DTR that planarly surrounds the CMOS transistor (region) and thehigh-voltage MOS transistor (region) from the outside penetrates throughthe buried insulating film BIL formed on the main surface of thesemiconductor substrate SUB in order to electrically separate the CMOStransistor (region) and the high-voltage MOS transistor (region) fromtheir outside regions, and the element isolation region DTR divides theburied insulating film BIL into two left and right parts. Furthermore,the substrate contact SCN also penetrates through the buried insulatingfilm BIL formed on the main surface of the semiconductor substrate SUB,and divides the buried insulating film BIL into two left and rightparts.

For example, an interlayer insulating film II including the siliconoxidation film is formed over the main surface of the semiconductorsubstrate SUB (p-type epitaxial layer PE2) on which the elementisolation region DTR is formed, so as to cover the CMOS transistor andthe high-voltage MOS transistor. For example, an interlayer insulatingfilm II1 (insulating film) including the silicon oxidation film isformed so as to cover an upper surface of the interlayer insulating filmII. This interlayer insulating film II1 is formed so as to cover theCMOS transistor and the high-voltage MOS transistor (element) in thesame way as the interlayer insulating film II, and is formed so as tocover also a side wall and a bottom wall of the element isolation regionDTR formed on the main surface of the semiconductor substrate SUB in theoutside in the plan view of the CMOS transistor region and thehigh-voltage MOS transistor region.

The concave portion TI formed so as to extend to the inside from themain surface of the semiconductor substrate SUB has: a first concaveportion TI constituting the substrate contact SCN in the substrateelectrode region; and a second concave portion TI constituting theelement isolation region DTR that is formed so as to surround, from theoutside, the CMOS transistor region and the high-voltage MOS transistorregion in the plan view, the second concave portion TI being differentfrom the first concave portion. Both the first and second concaveportions TI are formed so as to extend to the inside from the mainsurface of the semiconductor substrate SUB.

The interlayer insulating film II1 formed over the main surface of thesemiconductor substrate SUB is formed so as to fill a part of the insideof the concave portion TI constituting the element isolation region DTRformed on the main surface of the semiconductor substrate SUB. However,the interlayer insulating film II1 does not completely fill the insideof the concave portion TI constituting the element isolation region DTR,but partially fills it. For this reason, the capped hollow AG is formedinside the concave portion TI constituting the element isolation regionDTR. As a result, in the element isolation region DTR, particularly theside wall and the bottom wall inside the concave portion TI are formedso as to be covered by the interlayer insulating film II1. Theinterlayer insulating film II1 preferably covers the entire side walland bottom wall of the concave portion TI constituting the elementisolation region DTR.

The hollow AG in the element isolation region DTR extends along adirection (vertical direction of FIG. 4) where the concave portion TIextends, and has a length shorter than a length (in the verticaldirection of FIG. 4) of the concave portion TI and a width narrower thana width (in a horizontal direction of FIG. 4) of the concave portion TI.However, the hollow AG preferably has a length comparatively close tothe length of the concave portion TI in relation to the verticaldirection of FIG. 4. In other words, the hollow AG preferably extendsfrom a region near the main surface of the semiconductor substrate SUB(p-type epitaxial layer PE2) to a region near the bottom wall of theconcave portion TI.

In addition, the hollow AG is preferably formed so that a width of anupper part is narrower than that of a lower part in FIG. 4. That is,although, in FIG. 3, the hollow AG entirely is illustrated so as to havea substantially constant width, actually, the hollow AG preferably has atapered shape as shown in FIG. 4. An upper end of the hollow AG havingthe tapered shape is capped, and the hollow AG is formed as a bubblewhose periphery is surrounded by the interlayer insulating film II1.

Also in the substrate contact SCN of the substrate electrode region, inthe same way as the element isolation region DTR, the concave portion TIis formed so as to extend in the vertical direction of FIG. 4 from onemain surface (main surface in contact with the interlayer insulatingfilm II1) of the semiconductor substrate SUB to the approximately samedepth (for example, in the p-type impurity region PSB) as the bottomsurface of the concave portion TI of the element isolation region DTR.

The interlayer insulating film II1 formed over the main surface of thesemiconductor substrate SUB is formed so as to fill a part of an insideof the first concave portion TI constituting the substrate contact SCNformed on the main surface of the semiconductor substrate SUB. Althoughthis interlayer insulating film II1 is formed so as to cover a side wallof the first concave portion TI, the interlayer insulating film II1 isformed so as to expose the semiconductor substrate SUB on the bottomwall of the concave portion TI without covering at least a part (forexample, a central part) of the bottom wall thereof. The interlayerinsulating film II1 preferably covers an entire side wall of the firstconcave portion TI constituting the substrate contact SCN.

The substrate contact conductive layer CDL as a first conductive layerthat extends in the direction (vertical direction of FIG. 4) in whichthe concave portion TI extends inside the first concave portion TI ofthe substrate contact SCN (for example, a central part surrounded by theinsulating film II1 in the concave portion TI) is formed so as to reachthe bottom wall of the concave portion TI from one main surface (mainsurface on an opposite side of the main surface in contact with thesemiconductor substrate SUB) of the interlayer insulating film II1. Inother words, the substrate contact conductive layer CDL of the substratecontact SCN is formed so as to fill an inside of the hollow AG similarto a contact hole CH1A formed in some regions in the interlayerinsulating film II1 and the concave portion TI, and the above-describedelement isolation region DTR.

In addition, the wiring layer ICL1 is formed over one main surface ofthe interlayer insulating film II1 in which the first concave portion TIof the substrate contact SCN is formed, and this wiring layer ICL1 isformed so as to cover the substrate contact conductive layer CDL of thesubstrate contact SCN. Accordingly, the substrate contact conductivelayer CDL of the substrate contact SCN is electrically coupled to bothof the wiring layer ICL1 and the semiconductor substrate SUB (p-typeimpurity region PSB).

The wiring layer ICL1 is formed not only in a region right over thesubstrate contact conductive layer CDL of the substrate contact SCN, butalso in regions right over regions NR and PR as the source/drain regions(conductive portions) of the CMOS transistor and the high-voltage MOStransistor, over one main surface of the interlayer insulating film II1.Between the above-described regions NR and PR, and the wiring layer ICL1formed right over the regions, there is formed the plug conductive layerPL1 that extends so as to penetrate through the interlayer insulatingfilm II and the interlayer insulating film II1 in the vertical directionof FIG. 4.

Meanwhile, the plug conductive layer PL1 as a second conductive layer isformed so as to fill an inside of a contact hole CH1B that has beenformed so as to reach the regions NR and PR of the CMOS transistor andthe high-voltage MOS transistor formed on the other main surface (onemain surface of the semiconductor substrate SUB) from one main surfaceof the interlayer insulating film II1. The plug conductive layer PL1electrically couples the wiring layer ICL1 located right thereover tothe regions NR and PR located right thereunder (elements such as theCMOS transistor).

The contact hole CH1A as a first hole portion extends in the verticaldirection of FIG. 4 so as to reach the bottom wall of the concaveportion TI through the inside of the first concave portion TI of thesubstrate electrode region from an upper surface (upper-side surface) ofthe interlayer insulating film II1, and to lead to the p-type impurityregion PSB where the bottom wall of the concave portion TI is arranged.In addition, the contact hole CH1B as a second hole portion is formed soas to reach the source/drain regions (conductive regions) of the CMOStransistor and the like from the upper surface (upper-side surface) ofthe interlayer insulating film II1.

The substrate contact conductive layer CDL of the substrate contact SCNas the first conductive layer, and the plug conductive layer PL1 as thesecond conductive layer are formed with the same material.

On an upper side of the wiring layer ICL1 (opposite side of thesemiconductor substrate SUB), an interlayer insulating film II2 isformed over the interlayer insulating film II1 so as to cover the wiringlayer ICL1. A contact hole CH2 is formed so as to reach an upper surfaceof the wiring layer ICL1 from one main surface (a side opposite to aside in contact with the interlayer insulating film II1) of theinterlayer insulating film II2, and a plug conductive layer PL2 isformed so as to fill an inside of the contact hole CH2. Namely, the plugconductive layer PL2 extends so as to penetrate through the interlayerinsulating film II2 in the vertical direction of FIG. 4. Above the plugconductive layer PL2, in the same way as the above, there are formed:interlayer insulating films 113 and 114; contact holes CH3 and CH4; plugconductive layers PL3 and PL4; and wiring layers ICL2, ICL3, and ICL4.Materials or the like of the above are all basically similar to those ofthe above-described interlayer insulating film II1, contact hole CH1,plug conductive layer PL1, and wiring layer ICL1. Furthermore, a patternof a glass coating film BM may be formed above the above-describedinterlayer insulating films 113 and 114, contact holes CH3 and CH4, plugconductive layers PL3 and PL4, and wiring layers ICL2, ICL3, and ICL4.

Next, using FIGS. 5 to 15, there will be explained a method formanufacturing the semiconductor chip CHP having the CMOS transistorregion, the high-voltage MOS transistor region, and the substrateelectrode region which are shown in FIG. 4 as the semiconductor deviceof one embodiment. Meanwhile, FIGS. 5 to 15 show a manufacturing methodof a configuration shown in FIG. 4 for each process, and each regionshown in FIGS. 5 to 15 is basically the same as each region shown inFIG. 4.

Referring to FIG. 5, as a semiconductor substrate, first, there isprepared the p-type impurity region PSB including a p-type impurityregion (p⁺ region as a first conductive-type substrate region) having acomparatively high concentration.

Referring to FIG. 6, the p-type epitaxial layer PE1 having acomparatively lower p-type impurity concentration than the p-typeimpurity region PSB is formed over one main surface (for example, anupper-side main surface) of the p-type impurity region PSB by using ausual epitaxial technology.

Referring to FIG. 7, an n-type impurity is implanted inside the p-typeepitaxial layer PE1 as shown by arrows in FIG. 7 by using a usual ionimplantation technology. Consequently, referring to FIG. 8, the n-typeburied layer NBL as an n-type (second conductive-type) diffusion layeris formed on the entire surface of the p-type epitaxial layer PE1 closerto the main surface (an upper side in FIG. 7) than the p-type impurityregion PSB.

Furthermore, referring to FIG. 8, a p-type impurity is implanted insidethe n-type buried layer NBL by using the usual ion implantationtechnology, and thus a p-type buried layer PBL as a p-type diffusionlayer may be formed on the entire surface of the main surface of then-type buried layer NBL. The p-type epitaxial layer PE2 having acomparatively lower p-type impurity concentration than the p-typeimpurity region PSB is further formed over the p-type buried layer PBLby using a usual epitaxial technology.

As described above, in the entire surface in the plan view, there isformed the semiconductor substrate SUB having thereinside the p-typeimpurity region PSB, the p-type epitaxial layer PE1, the n-type buriedlayer NBL, the p-type buried layer PBL, and the p-type epitaxial layerPE2.

Referring to FIG. 9, elements such as the CMOS transistor and the MOStransistor are formed at predetermined positions of the main surface(upper-side main surface in FIG. 9) of the semiconductor substrate SUBformed in each process of FIGS. 5 to 8.

Specifically, at the p-type epitaxial layer PE2 (or at the high-voltagen-type well region HNW shown in FIG. 3), the NMOS transistor is formedin the NMOS region of the CMOS transistor region, and the PMOStransistor is formed in the PMOS region thereof. The NMOS transistormainly has: the p-type well region PWR formed at the p-type epitaxiallayer PE2; the n⁺ region NR as the source region or the drain region(conductive portions); the gate insulating film GI; the gate electrodelayer GE; and the side wall insulating film SW. The PMOS transistormainly has: the n-type well region NWR formed at the p-type epitaxiallayer PE2; the p⁺ region PR as the source region or the drain region;the gate insulating film GI; the gate electrode layer GE; and the sidewall insulating film SW.

In addition, the high-voltage MOS transistor is formed at the p-typeepitaxial layer PE2 (or the high-voltage n-type well region HNW shown inFIG. 3) in the high-voltage MOS transistor region. The high-voltage MOStransistor mainly has: the n-type well region NWR; the n-type offset,region NOR; the p-type well region PWR; the n⁺ region NR; the p⁺ regionPR; the gate insulating film GI; the gate electrode layer GE; and theside wall insulating film SW.

The above-described CMOS transistor and MOS transistor may include thecobalt silicide layer SC. In addition, the buried insulating film BIL isformed in a region that planarly surrounds the above-described eachelement from the outside, the substrate electrode region, and a regionbetween the NMOS transistor and the PMOS transistor.

Referring to FIG. 10, the nitride film NF (refer to FIG. 4) may beincluded so as to cover the formed CMOS transistor and the high-voltageMOS transistor. In addition, the interlayer insulating film II includingthe silicon oxidation film is formed over the semiconductor substrateSUB, for example, by using a CVD (Chemical Vapor Deposition) method.

Referring to FIG. 11, a photoresist PHR is coated so as to cover theinterlayer insulating film II. This photoresist PHR is patterned by ausual photolithography technology. Anisotropic etching of the interlayerinsulating film II and the buried insulating film BIL is performed inorder using this patterned photoresist PHR as a mask. Consequently,there is formed a through-concave portion TIA that passes through theinterlayer insulating film II and the buried insulating film BIL. Afterthis, the photoresist PHR is removed by ashing or the like.

Referring to FIG. 12, anisotropic etching is applied to the p-typeepitaxial layer PE2 using the interlayer insulating film II as a mask.Consequently, the semiconductor substrate SUB (p-type epitaxial layerPE2) directly under the through-concave portion TIA is selectivelyremoved. Consequently, the concave portion TI is formed, for example, soas to penetrate through the p-type epitaxial layer PE2, the p-typeburied layer PBL, the n-type buried layer NBL, and the p-type epitaxiallayer PE1 to thereby reach the p-type impurity region PSB from thesurface of the semiconductor substrate SUB (p-type epitaxial layer PE2).This concave portion TI is preferably formed so as to penetrate throughthe n-type buried layer NBL to thereby reach the p-type impurity regionPSB.

In the manner as described above, the concave portion TI is formed thatextends the inside of the semiconductor substrate SUB from the mainsurface of the semiconductor substrate SUB, the concave portion TIeventually serving as the first concave portion and the second concaveportion. That is, in other words, the first concave portion TI and thesecond concave portion TI are simultaneously formed by the same etchingtreatment.

Referring to FIG. 13, the insulating film II1 (insulating film) isformed over each element and in the concave portion TI so as to coverthe interlayer insulating film II over each element and a surface of thep-type epitaxial layer PE2 of the substrate electrode region, and toform the capped hollow AG in the concave portion TI. Specifically, theinterlayer insulating film II1 is formed over the main surface of thesemiconductor substrate SUB, the side wall and the bottom wall of theconcave portion TI. Here, since an aspect ratio of the concave portionTI is high, and the (interlayer) insulating film II1 is difficult tofill an entire inside of the concave portion TI, the insulating film II1is not supplied to a center of the concave portion TI particularlyexcluding the side wall and the bottom wall thereof, and as a result,the bubble-like hollow AG is formed.

The above-described insulating film II1 is, for example, formed ofBP-TEOS with a thickness of 1320 nm, and a usual silicon oxidation film.The upper surface of this insulating film II1 is polished and removed bya CMP (Chemical Mechanical Polishing) method. However, the insulatingfilm II1 is not limited to an insulating film (BP-TEOS) containing aconductive impurity as described above, it may be, for example, theusual silicon oxidation film not containing the conductive impurity.

Here, the hollow AG formed in the concave portion TI preferably has alength (comparatively) near a length of the concave portion TI inrelation to the vertical direction of FIG. 13, i.e., has substantiallythe same length (in the vertical direction of FIG. 13) as the concaveportion TI. Namely, the hollow AG preferably extends from the regionnear the main surface of the semiconductor substrate SUB (p-typeepitaxial layer PE2) to the region near the bottom wall of the concaveportion TI. In addition, the hollow AG is formed so that a width isnarrower in the upper side (side near the main surface of thesemiconductor substrate SUB) of the concave portion TI of FIG. 13 thanin the lower side (side near the bottom wall of the concave portion TI)thereof. In other words, a thickness of the insulating film II1(interlayer insulating film II1) formed over the side wall of theconcave portion TI becomes thicker in the upper side of the concaveportion TI than in the lower side thereof.

As described above, in a process of FIG. 13, the insulating film II1 iseventually formed over the side walls and the bottom walls of both theconcave portion TI serving as the first concave portion TI, and theconcave portion TI serving as the second concave portion TI.

Referring to FIG. 14, the photoresist PHR is coated so as to cover theinterlayer insulating film II1. The usual photolithography technique isperformed on this photoresist PHR, and thus patterning is performed sothat an opening is formed right over the conductive portions(source/drain regions) of the CMOS transistor and the high-voltage MOStransistor, and right over the inside of the concave portion TI in thesubstrate electrode region. Anisotropic etching of the interlayerinsulating film II1 is performed by using this patterned photoresist PHRas a mask.

Consequently, in the CMOS transistor region and the high-voltage MOStransistor region, the contact hole CH1B as the second hole portion isformed so as to reach the conductive portions (source/drain regions) ofthe CMOS transistor and the high-voltage MOS transistor from anuppermost surface of the interlayer insulating film II1. In addition, atthis time, in the substrate electrode region, the contact hole CH1A asthe first hole portion is formed so as to reach the inside of theconcave portion TI, particularly, the hollow AG in the concave portionTI.

The contact hole CH1A formed here has an aspect in which a portionformed by etching treatment in the same way as the contact hole CH1B,and the originally existing hollow AG have been coupled to beintegrated. After the contact hole CH1A is integrated with the hollowAG, there is etched the insulating film II1 formed over the bottom wallof the concave portion TI existing right under the hollow AG, and thecontact hole CH1A is formed so as to reach the bottom wall (p-typeimpurity region PSB) of the concave portion TI from the bottom wall ofthe hollow AG, and to eventually expose the semiconductor substrate SUB(p-type impurity region PSB) on the bottom wall of the concave portionTI. More specifically, as to the contact hole CH1A, the interlayerinsulating film II1 is first etched so that the interlayer insulatingfilm II1 reaches the hollow AG in the concave portion TI from the uppersurface of the interlayer insulating film II1 toward the lower side ofFIG. 14. At this time, the etching is performed so as to reach thesemiconductor substrate SUB (for example, the p-type impurity regionPSB) on the bottom wall of the concave portion TI while leaving theinsulating film II1 over the side wall of the concave portion TI, inother words, so as to remove the insulating film II1 over the bottomwall of the concave portion TI (sandwiched between the bottom wall ofthe concave portion TI and the bottom wall of the hollow AG).

On the other hand, the contact hole CH1B is formed by the same etchingtreatment as etching the interlayer insulating film II1 in a lowerdirection of FIG. 14 in order to form the contact hole CH1A (beforereaching the hollow AG). Namely, the contact hole CH1B is formed so asto reach the conductive portions (source/drain regions and the like) ofthe element from the upper surface of the interlayer insulating filmII1.

The contact hole CH1A and the contact hole CH1B are formed by the sameetching treatment. As described above, the hollow AG as the bubble inwhich the insulating film II1 formed in the concave portion TI and soforth are not arranged is formed so as to extend to an uppermost portionof the concave portion TI, that is, to the vicinity of the main surfaceof the semiconductor substrate SUB (p-type epitaxial layer PE2). Forthis reason, there is no large difference between a distance of theregions NR, PR and the like as the conductive portions the contact holeCH1B should reach, from the upper-side surface of the interlayerinsulating film II1, and a distance of the hollow AG that the contacthole CH1A should reach therefrom.

Accordingly, there is no large difference between a depth into which theinterlayer insulating film II1 should be etched in order to form thecontact hole CH1A, and a depth into which the interlayer insulating filmII1 should be etched in order to form the contact hole CH1B. For thisreason, it becomes possible to form the contact hole CH1A and thecontact hole CH1B which completely differ in depth at a glance, by thesame etching treatment.

The contact hole CH1A in the concave portion TI of the substrateelectrode region is integrated with the hollow AG by the above-describedetching treatment, and subsequently, further the insulating film II1over the bottom wall of the concave portion TI existing right under thehollow AG is removed. For this reason, the contact hole CH1A is formedso as to reach the bottom wall of the concave portion TI from theupper-side surface of the interlayer insulating film II1.

Widths (in a horizontal direction of FIG. 14) of the contact hole CH1Aand the contact hole CH1B are preferably narrower than the width (in thehorizontal direction of FIG. 14) of the concave portion TI for formingthe element isolation region DTR. According to the above-describedconfiguration, the contact hole CH1A can be formed so as to reach thebottom wall of the concave portion TI through the inside of the concaveportion TI. In addition, from the point of view that the contact holeCH1A and the contact hole CH1B are formed by the same etching treatment,the widths (in the horizontal direction of FIG. 14) of the both arepreferably equal to each other.

As one example, it is preferable that the widths of the contact holeCH1A and the contact hole CH1B are set to be 0.4 μm, and that the widthof the concave portion TI for forming the element isolation region DTR(and the substrate contact SCN) is set to be 0.8 μm. When the elementisolation region DTR is formed very deep, the width of the concaveportion TI for forming the element isolation region DTR (and thesubstrate contact SCN) needs to be set wide, but when theabove-described depth is approximately 20 μm or less, the width of theconcave portion TI can be set to be 0.8 μm.

Referring to FIG. 15, after the photoresist PHR is removed by asking andso forth, thin films of titanium (Ti) and titanium nitride (TiN) areformed as barrier metal so as to cover the interlayer insulating filmII1, and wall surfaces inside the contact holes CH1A and CH1B, forexample, by a usual sputtering method, and subsequently, a metal thinfilm of tungsten (W) is formed by a plasma CVD method. Next, theabove-described barrier metal and the metal thin film over theinterlayer insulating film II1 are removed by etch back.

In this way, the plug conductive layer PL1 including the metal thin filmof tungsten is formed inside the contact hole CH1B, and simultaneously,the substrate contact conductive layer CDL including the metal thin filmof tungsten is formed inside the contact hole CH1A. Namely, thesubstrate contact conductive layer CDL and the plug conductive layer PL1are formed by the same film-forming treatment, and both are formed ofthe same material. The plug conductive layer PL1 is formed so as to beelectrically coupled to the source/drain regions (conductive portions)of the CMOS transistor and the high-voltage MOS transistor. Thesubstrate contact conductive layer CDL is formed so as to beelectrically coupled to the semiconductor substrate SUB (for example,the p-type impurity region PSB).

Meanwhile, the substrate contact conductive layer CDL may be formed sothat a hollow AGA as a bubble similar to the above-described hollow AGis formed thereinside. However, the hollow AGA is omitted in thefollowing each drawing.

As described above, although the plug conductive layer PL1 and thesubstrate contact conductive layer CDL may be formed of the metal thinfilm of tungsten, they may be a metal thin film formed of, for example,aluminum.

Referring to FIG. 16, the wiring layer ICL1 is formed over theinterlayer insulating film II1 so as to be in contact with uppersurfaces of the plug conductive layer PL1 and the substrate contactconductive layer CDL, and to electrically couple these to the conductiveportion of each element or the semiconductor substrate SUB (p-typeimpurity region PSB). Although this wiring layer ICL1 is preferablyformed as a stacked structure of titanium nitride, and alloy (AlCu) ofcopper and aluminum, for example, by the usual sputtering method, it maybe formed of the same material as the above-described plug conductivelayer PL1 and substrate contact conductive layer CDL. As one example,for example, a stacked structure of titanium nitride of 26.5 nm and AlCuof 450 nm is formed.

As described above, in the substrate electrode region, the substratecontact conductive layer CDL is formed in the contact hole CH1A in theconcave portion TI. This substrate contact conductive layer CDL isformed so as to electrically couple the semiconductor substrate SUB(p-type impurity region PSB) to the wiring layer ICL1. In addition, inthe CMOS transistor region and the high-voltage MOS transistor region,the plug conductive layer PL1 is formed in the contact hole CH1B, andthis plug conductive layer PL1 is formed so as to electrically couple(the conductive portion of) the element, such as the CMOS transistor, tothe wiring layer ICL1.

After that, although each layer on the upper side of the wiring layerICL1 as shown in FIG. 4 is formed by basically repeating formationprocesses similar to the above-described formation processes of theinterlayer insulating film II1, the plug conductive layer PL1, and thewiring layer ICL1, detailed explanation of the processes are omitted.

Next, operational effects of the present embodiment will be explained.

In the present embodiment, by the same etching treatment, formed are thecontact hole CH1A as the first hole portion formed in the concaveportion TI in order to form the substrate contact SCN (substrate contactconductive layer CDL) in the substrate electrode region, and the contacthole CH1B as the second hole portion formed in the CMOS transistorregion and so forth. For this reason, the number of masks needed for theetching treatment and a time required for treatment can be reduced, forexample, compared with a case where the contact hole CH1A and thecontact hole CH1B are formed by different etching treatment. As aresult, cost required for treatment can be significantly reduced.

In the present embodiment, the contact hole CH1A extends in a verticaldirection of FIG. 4 so as to reach the bottom wall of the concaveportion TI through the first concave portion TI in the substrateelectrode region from the upper surface of the interlayer insulatingfilm II1, and to lead to the p-type impurity region PSB where the bottomwall of the concave portion TI is arranged. In addition, the contacthole CH1B is formed so as to reach the source/drain regions (conductiveregions) of the CMOS transistor and so forth from the upper surface ofinterlayer insulating film II1. As a result of this, it can be verifiedthat the contact hole CH1A and the contact hole CH1B are formed by thesame etching treatment.

A first reason that can be achieved the process of forming the contacthole CH1A and the contact hole CH1B by the same etching treatment isthat the hollow AG that is not filled with the insulating film II1 isformed in the concave portion TI of the substrate electrode region wherethe contact hole CH1B is formed. Namely, if the hollow AG is notpresent, a depth (substantially equal to a sum of a thickness of theinterlayer insulating film II1 and a depth of the concave portion TI)that should be etched to form the contact hole CH1A becomes extremelylarge compared with a depth (thickness of the interlayer insulating filmII1) that should be etched to form the contact hole CH1B, and thus itbecomes difficult to etch both in the same process. Since the aspectratio of the concave portion TI is extremely high, the interlayerinsulating film II1 only partially fills the inside of the concaveportion TI, and the hollow AG is formed, etching is substantiallysufficient if progressing to an uppermost portion of the hollow AG, inorder to form the contact hole CH1A.

A second reason that can be achieved the process of forming the contacthole CH1A and the contact hole CH1B by the same etching treatment isthat the contact hole CH1A is formed so as to penetrate through only thesemiconductor region of the semiconductor substrate SUB. Namely, if thecontact hole CH1A needs to penetrate through the insulating film buriedinside a so-called SOI substrate in the contact hole CH1A being formed,the filling insulating film is thick, much time etc. are needed foretching, and thus it becomes difficult to complete etching by the sameetching treatment as in the contact hole CH1B. Since the semiconductorsubstrate SUB used in the present embodiment includes only thesemiconductor region having conductivity, and it does not have theburied insulating film as described above, the contact hole CH1A can beeasily formed with substantially the same etching amount as in thecontact hole CH1B.

Next, in the present embodiment, the first concave portion TI forforming the substrate contact SCN and the second concave portion TI forforming the element isolation region DTR are formed by the same etchingtreatment as shown in FIGS. 11 and 12. In addition, the insulating filmII1 in the concave portion TI for forming the substrate contact SCN, andthe insulating film II1 in the concave portion TI for forming theelement isolation region DTR are formed by the same film-formingtreatment as shown in FIG. 13. As a result, the number of processes, atreatment time, and manufacturing cost can be reduced compared with acase where the above-described two insulating film II1 are formed asseparate treatment.

In the present embodiment, the concave portion TI formed for thesubstrate contact SCN in the substrate electrode region is formed by thesame processes as in the concave portion TI that formed for the elementisolation region DTR such as the CMOS transistor region. In other words,in the present embodiment, the substrate contact SCN is formed utilizinga part of the concave portion TI essentially formed in order to form theelement isolation region DTR. As described above, formation of thecontact hole CH1A for forming the substrate contact SCN becomes easierby the presence of the hollow AG compared with a case, supposing thatthe hollow AG is not present. For this reason, the substrate contact SCNcan be formed more easily utilizing the concave portion TI formed in theother process (process of forming the element isolation region DTR)without performing an additional process for forming the substratecontact SCN. Namely, the present embodiment has a practical advantage ina case where there is a request to lead out a potential of a back sideof the substrate from the surface of a front side of the semiconductorsubstrate SUB by using the substrate contact SCN.

Since the hollow AG is formed in the element isolation region DTR, astress near the concave portion TI of the element isolation region DTRin the semiconductor substrate SUB can be reduced compared with a case,supposing that the hollow AG is not formed.

In addition, the substrate contact conductive layer CDL that fills theinside of the contact hole CH1A, and the plug conductive layer PL1 thatfills the inside of the contact hole CH1B are formed as the samematerial by the same film-forming treatment. Also because of this, thenumber of processes, the treatment time, and the manufacturing cost canbe reduced compared with a case where the substrate contact conductivelayer CDL and the plug conductive layer PL1 are formed by differentfilm-forming treatment.

Next, referring to FIG. 17, although a semiconductor chip CHP as acomparative example of the present embodiment has a configurationbasically similar to the semiconductor chip CHP of the presentembodiment of FIG. 3, a configuration of a substrate contact in asubstrate electrode region is different from that of the presentembodiment. Specifically, the substrate contact is formed of: the p-typeburied layer PBL and a deep p-type diffusion layer DPW that have beenformed as the same layer as the p-type epitaxial layer PE2. Morespecifically, in relation to a vertical direction of FIG. 17, the deepp-type diffusion layer DPW, the p-type buried layer PBL, the p-typeepitaxial layer PE1, and the p-type impurity region PSB are aligned inthat order from a main surface side of the upper side of thesemiconductor substrate SUB (p-type epitaxial layer PE2), and thesemutually continue in relation to the vertical direction of FIG. 17.Furthermore, in FIG. 17, the interlayer insulating film II is notformed, but the interlayer insulating film II1 is formed so as to coverthe main surface of the semiconductor substrate SUB.

Since both the deep p-type diffusion layer DPW and the p-type buriedlayer PBL are regions containing the p-type impurity, all the regionsserve as the regions containing the p-type impurity in the substrateelectrode region. For this reason, for example, it becomes possible toelectrically couple the wiring layer formed over the p-type epitaxiallayer PE2 (deep p-type diffusion layer DPW) to the p-type impurityregion PSB, in the substrate electrode region.

On the other hand, in the CMOS transistor region and the high-voltageMOS transistor region, the n-type buried layer NBL is formed sinceelectrical coupling is cut off between, for example, the high-voltagen-type well region HNW (p-type epitaxial layer PE2) and the p-typeimpurity region PSB below the semiconductor substrate SUB, where theelement is formed. If this n-type buried layer NBL is formed in thesubstrate electrode region, a substrate potential cannot be taken outsince p-n junction is formed in the region. For this reason, in thecomparative example of FIG. 17, the n-type buried layer NBL needs to bepatterned so as not to be formed in the substrate electrode region (inother words, so that the n-type buried layer NBL is formed only in theCMOS transistor region and the like).

However, if as in the present embodiment, the substrate contact SCNformed utilizing the same concave portion as the concave portion TI forforming the element isolation region DTR is used for the substrateelectrode region, the n-type buried layer NBL similar to the CMOStransistor region and the like may be formed also in the substrateelectrode region. This is because, as to the substrate contact SCN,conduction with the p-type impurity region PSB is made by the substratecontact conductive layer CDL in the concave portion TI, and because, aslong as the substrate contact SCN is used, a conductive type of theimpurities that fill the semiconductor region around the substratecontact SCN does not affect the conductivity of the substrate contactSCN. For this reason, in the present embodiment, patterning need not beperformed so that the n-type buried layer NBL is locally (selectively)formed, and the n-type buried layer NBL may be formed on the entiresemiconductor substrate SUB in the plan view.

Accordingly, a process of patterning the n-type buried layer NBL can beskipped, and preparation of a mask for patterning the n-type buriedlayer NBL becomes unnecessary. Therefore, processes can be moresimplified, and manufacturing cost can be reduced.

In addition, referring to perspective diagrams of FIGS. 18A and 18B, bythe application of the substrate contact SCN of the present embodiment,an electric resistance of the substrate contact can be reduced comparedwith a case of using the deep p-type diffusion layer DPW and thesubstrate contact including the p-type buried layer PBL as in thecomparative example. Here, the electric resistance of the substratecontact means an electric resistance value from the upper-side surfaceof the p-type epitaxial layer PE2, which is an uppermost layer of thesemiconductor substrate SUB, to the upper-side surface of the p-typeimpurity region PSB, which is a lowermost layer of the semiconductorsubstrate SUB.

For this reason, if the present embodiment is applied, a width W1 (inrelation to a horizontal direction of FIG. 18A) of the substrate contactSCN shown in FIG. 18A can be made smaller than a width W2 of thesubstrate contact shown in FIG. 18B. This is because it is necessary todeeply form a diffusion layer by performing heat treatment for a longtime, for example, when the deep diffusion layer DPW is formed as acomponent member of the substrate contact as in FIG. 18B, thus a regionof the diffusion layer becomes excessively wide in the plan view, and anarea of the substrate contact may increase.

As a result, also in a case where a depth Dl of the substrate contactSCN shown in FIG. 18A and a depth Dl of the substrate contact shown inFIG. 18B are equal to each other, the area occupied by the substratecontact can be made smaller in the plan view in FIG. 18A compared withFIG. 18B. Accordingly, a size of the semiconductor chip CHP (refer toFIG. 1) in which the semiconductor device is formed can be decreased.

Second Embodiment

The substrate contact SCN in one embodiment may be formed as a drainelectrode electrically coupled to a drain region of a so-called verticalMOS transistor as an element.

Referring to FIG. 19, the semiconductor substrate SUB of the presentembodiment has a configuration in which the p-type impurity region PSB,the p-type epitaxial layer PE1, the n-type buried layer NBL, and thehigh-voltage n-type well region HNW have been stacked in this order. Inaddition, the semiconductor substrate SUB has the p-type epitaxial layerPE2 as the same layer as the high-voltage n-type well region HNW aroundthe high-voltage n-type well region HNW via the element isolation regionDTR.

A vertical element region is formed in the high-voltage n-type wellregion HNW, and a plurality of vertical MOS transistors is arranged inthe vertical element region so as to align in a direction along the mainsurface of the semiconductor substrate SUB. Each vertical MOS transistormainly has: the deep p-type diffusion layer DPW; the plug conductivelayer PL1; the substrate contact SCN; a source wiring layer SO; and adrain wiring layer DR. In addition to that, there are shown in FIG. 19:the gate insulating film GI constituting the vertical MOS transistor;the gate electrode layer GE; and a buried insulating film BIL.

The deep p-type diffusion layer DPW is the p-type impurity region as thesource region formed in the high-voltage n-type well region HNW. Theplug conductive layer PL1 is formed so as to penetrate through theinterlayer insulating film II and the interlayer insulating film II1 inthe same way as the plug conductive layer PL1 of the First Embodiment,and is formed so as to reach the n⁺ region NR and the p⁺ region PR,which will be mentioned later, formed at the deep p-type diffusion layerDPW. The source wiring layer SO corresponds to the wiring layer ICL1 ofthe First Embodiment, and is formed so as to cover the plug conductivelayer PL1.

The substrate contact SCN in the present embodiment has a configurationin which the insulating film II1 and the substrate contact conductivelayer CDL have been formed inside the concave portion TI in the same wayas the substrate contact SCN of the First Embodiment. In FIG. 19, as oneexample, the substrate contact SCN as the drain electrode extends so asto reach an inside of the n-type buried layer NBL as the drain regionfrom the main surface of the semiconductor substrate SUB, andelectrically couples the drain wiring layer DR to the n-type buriedlayer NBL. The drain wiring layer DR corresponds to the wiring layerICL1 of the First Embodiment, and is formed so as to cover the substratecontact SCN. In addition, the element isolation region DTR in thepresent embodiment also has a configuration in which the insulating filmII1 and the hollow AG have been formed inside the concave portion TI inthe same way as the element isolation region DTR of the FirstEmbodiment.

The n⁺ region NR, the p⁺ region PR, and the n⁺ region NR are arranged soas to align in this order, on the main surface of the semiconductorsubstrate SUB (high-voltage n-type well region HNW) in which the deepp-type diffusion layer DPW as the source region is formed.

Among these, the n⁺ region NR is the region where the source wiringlayer SO and the high-voltage n-type well region HNW, and the n-typeburied layer NBL and the drain region are electrically coupled to eachother by utilizing an electric field effect generated in thehigh-voltage n-type well region HNW directly under the gate electrodelayer GE and the gate insulating film GI. In addition, the p⁺ region PRis arranged in order to constitute a so-called back gate structure ofelectrically coupling the p⁺ region PR to the deep p-type diffusionlayer DPW right thereunder.

The configuration of the present embodiment differs in the above pointsas compared with the configuration of the First Embodiment, and sincethe other points are similar to the configuration of the FirstEmbodiment, the same symbol is attached to the same element, andexplanation thereof is not repeated.

Next, operational effects of the present embodiment will be explainedwith reference to a comparative example of FIG. 20. Meanwhile, althoughthe operational effects similar to the First Embodiment are basicallyexerted also in the present embodiment, here will be explainedadditional operational advantage to the operational advantage of theFirst Embodiment.

Referring to FIG. 20, although a semiconductor chip CHP as thecomparative example of the present embodiment has a configurationbasically similar to the semiconductor chip CHP of the presentembodiment of FIG. 19, a drain electrode is not the substrate contactSCN, but is formed of a deep n-type diffusion layer DNW extending so asto reach the n-type buried layer NBL from the main surface of thesemiconductor substrate SUB. Although FIG. 20 differs from FIG. 19 inthis point, the other points are basically similar to FIG. 19, and thusthe same symbol is attached to the same element and explanation thereofis not repeated.

The drain region is formed using the substrate contact SCN as in thepresent embodiment, and thus an electric resistance of the drain regioncan be significantly reduced compared with the case where the drainregion is formed of the deep n-type diffusion layer DNW. As a result,performance of a semiconductor device (semiconductor element) mounted onthe semiconductor chip CHP can be significantly enhanced.

In addition, when the deep n-type diffusion layer DNW is formed as thedrain region, prolonged heat treatment needs to be performed, thus adiffusion layer widens, and an area thereof in the plan view becomeslarge, but if the drain region is formed as the substrate contact SCN,an area in the plan view of the drain region can be decreased. For thisreason, in the present embodiment, a size of the semiconductor chip CHP(refer to FIG. 1) in which the semiconductor device is formed can bedecreased.

Third Embodiment

The substrate contact SCN (substrate contact conductive layer CDL) inone embodiment may have an active barrier region constituting aso-called active barrier structure.

Referring to FIG. 21, the semiconductor substrate SUB of the presentembodiment has a configuration in which, for example, the p-typeimpurity region PSB, the p-type epitaxial layer PE1, and the p-type wellregion PWR have been stacked in this order. In addition, also in thesemiconductor chip CHP of the present embodiment, in the same way as thesemiconductor chip CHP of the First Embodiment, the semiconductorsubstrate SUB has a CMOS transistor region (first element formationregion) and a high-voltage MOS transistor region (second elementformation region).

The CMOS transistor region of FIG. 21 has: the p-type epitaxial layerPE1; the n-type buried layer NBL; and the high-voltage n-type wellregion HNW in the same way as the CMOS transistor region of the FirstEmbodiment of FIG. 3. However, the high-voltage MOS transistor region ofFIG. 21 is simplified and shown so as to have: the p-type epitaxiallayer PE1; the n-type buried layer NBL; the deep n-type diffusion layerDNW; the n-type well region NWR; and the n⁺ region NR. The high-voltageMOS transistor region of FIG. 21 may have such a configuration, or mayhave a configuration similar to the high-voltage MOS transistor regionof FIG. 3.

Also in FIG. 21, in the same way as FIG. 3, the element isolation regionDTR is formed so as to surround the CMOS transistor region and thehigh-voltage MOS transistor region, and has a configuration in which theinsulating film II1 and the hollow AG have been formed inside theconcave portion TI. In addition, the substrate electrode region of FIG.21 is formed in a region where the p-type epitaxial layer PE1 and thep-type well region PWR have been stacked over the p-type impurity regionPSB, and in the substrate electrode region, in the same way as thesubstrate electrode region of the First Embodiment of FIG. 3, there isformed the substrate contact SCN having a configuration in which theinsulating film II1 and the substrate contact conductive layer CDL havebeen formed inside the concave portion TI. The substrate contact SCN is,for example, coupled to a ground terminal GND.

In FIG. 21, the CMOS transistor region and the high-voltage MOStransistor region are located apart from each other in relation to adirection (horizontal direction of FIG. 21) along the main surface ofthe semiconductor substrate SUB. An active barrier region is formed at aposition between the CMOS transistor region and the high-voltage MOStransistor region.

An active barrier structure includes: a second conductive-type (n-type)second region that has a configuration in which the n-type buried layerNBL, the deep n-type diffusion layer DNW, the n-type well region NWR,and the n⁺ region NR have been stacked in this order; the substratecontact SCN that has a configuration similar to the other Embodiments;and the wiring layer ICL1 as a coupling conductive layer thatelectrically couples the second region to the substrate contact SCN.That is, the substrate contact conductive layer CDL of the substratecontact SCN is formed so as to penetrate through the interlayerinsulating films II1 and II, the p-type well region PWR, and the p-typeepitaxial layer PE1 to thereby reach the p-type impurity region PSB fromthe uppermost surface of the interlayer insulating film II1.

Since the above-described substrate contact SCN is formed so as topenetrate through the p-type well region PWR and the p-type epitaxiallayer PE1 to reach the p-type impurity region PSB, it functions as ap-type region of the active barrier structure. The substrate contact SCNas the p-type region of the active barrier structure also has aconfiguration in which the insulating film II1 and the substrate contactconductive layer CDL have been formed inside the concave portion TI inthe same way as the substrate contact SCN of the substrate electroderegion.

Ohmic-coupled are the n-type region and the substrate contact SCN(particularly, the substrate contact conductive layer CDL) constitutingthe active barrier structure. Although the ohmic-coupled n-type regionand substrate contact SCN are not shown, for example, they may becoupled to a ground terminal.

In FIG. 21 (in the same way as the other Embodiments), the p-typeimpurity region PSB of the semiconductor substrate SUB is formed at theentire surface in the plan view of the semiconductor substrate SUB.Namely, the p-type impurity region PSB is formed as a firstconductive-type (p-type) first region so as to extend in the directionalong the main surface of the semiconductor substrate SUB from the CMOStransistor region at least to the high-voltage MOS transistor regionthrough the active barrier region.

The second conductive-type (n-type) second region constituting theactive barrier structure is formed at the main surface of thesemiconductor substrate SUB in the active barrier region so as toconstitute p-n junction with a first conductive-type region (p⁺ regionconstituting the p-type impurity region PSB) including the first region.Namely, the n⁺ region NR that forms an uppermost layer in the secondregion is formed at the main surface of the semiconductor substrate SUB(p-type well region PWR). In addition, the n-type buried layer NBL thatforms a lowermost layer in the second region is formed in the p-typeepitaxial layer PE1.

Here will be simply explained an operating principle of the activebarrier structure in the semiconductor chip CHP of FIG. 21. For example,when a negative potential is applied to the CMOS transistor region, andelectrons are absorbed in the p-type impurity region PSB of thesemiconductor substrate SUB from the elements, such as the CMOStransistor, the electrons move toward a high-voltage MOS transistorregion side that has a higher potential than the CMOS transistor region,i.e., a right side of FIG. 21. A part of the electrons is absorbed inthe n-type region of the active barrier structure. Holes similar to theabsorbed electrons then move to the p-type impurity region PSB from thesubstrate contact SCN (that functions as the p-type region) of theactive barrier structure. Consequently, a potential decreases near thesubstrate contact SCN (that functions as the p-type region) of theactive barrier structure, which becomes a potential barrier for theelectrons that try to move toward the high-voltage MOS transistorregion. For this reason, the electrons become hard to move in adirection of the high-voltage MOS transistor region, and are likely tohead to a deep region side (lower side of FIG. 21) of the p-typeimpurity region PSB. As described above, can be suppressed malfunctionof the high-voltage MOS transistor due to unintentional entering of theelectrons into the high-voltage MOS transistor region.

The configuration of the present embodiment differs in the above pointsas compared with the configuration of the First Embodiment, and sincethe other points are similar to the configuration of the FirstEmbodiment, the same symbol is attached to the same element, andexplanation thereof is not repeated.

Next, operational advantage of the present embodiment will be explainedwith reference to a comparative example of FIG. 22. Meanwhile, althoughthe operational advantage similar to the First Embodiment are basicallyexerted also in the present embodiment, here, there will be explainedadditional operational advantage to the operational advantage of theFirst Embodiment.

Referring to FIG. 22, although a semiconductor chip CHP as thecomparative example of the present embodiment has a configurationbasically similar to the semiconductor chip CHP of the presentembodiment of FIG. 21, the p-type region of the active barrier structureis formed of the p⁺ region PR having a comparatively high impurityconcentration instead of the substrate contact SCN. Although FIG. 22differs from FIG. 21 in this point, FIG. 22 is basically similar to FIG.21 in the other points. Therefore, the same symbol is attached to thesame element and explanation thereof is not repeated.

The p-type region of the active barrier structure is formed using thesubstrate contact SCN as in the present embodiment, and thus an electricresistance of the p-type region can be reduced compared with a casewhere the p-type region is formed of the p-type impurity region PR. As aresult, movement of the holes from the substrate contact SCN as thep-type region to the p-type impurity region PSB of the substrate isperformed more smoothly, and an efficiency of the active barrierstructure that forms a potential barrier of the electrons can beenhanced. For this reason, a configuration of the present embodiment canenhance a function of the active barrier structure further more than theconfiguration of the comparative example.

Fourth Embodiment

Referring to FIGS. 23 to 25, in the present embodiment, all the concaveportions TI essentially formed for the formation of the elementisolation region DTR are used in order to form the substrate contactSCN. In this point, the present embodiment is different from the FirstEmbodiment in which only a part of the concave portion TI (i.e., onlythe first concave portion TI formed in the substrate electrode region)essentially formed for the formation of the element isolation region DTRis used in order to form the substrate contact SCN, and the otherconcave portions TI are used as the second concave portion TI forforming the element isolation region DTR.

Specifically, referring to FIG. 23, in a semiconductor chip CHP of thepresent embodiment, the substrate contact SCN is formed in the region(around the logic portion LG and the output driver portion HV) where theelement isolation region DTR is formed in the semiconductor chip CHP ofFIG. 1. In other words, in the semiconductor chip CHP of the presentembodiment, the logic portion LG and the output driver portion HV aresurrounded by the substrate contact SCN in the plan view.

The element isolation region DTR is not formed in FIG. 23. In addition,in FIG. 23, the substrate contact SCN is not formed in the region wherethe substrate contact SCN is formed in FIG. 1.

Similarly, referring to FIGS. 24 and 25, in the present embodiment, thesubstrate electrode region (substrate contact SCN) is formed so as tosurround the CMOS transistor region and the high-voltage MOS transistorregion. In this point, the present embodiment is different from theFirst Embodiment (FIGS. 3 and 4) in which the element isolation regionDTR is formed so as to surround the CMOS transistor region and thehigh-voltage MOS transistor region.

Meanwhile, although the substrate contact SCN of FIGS. 24 and 25 isarranged at a position more slightly apart from the CMOS transistorregion or the like than the element isolation region DTR of FIGS. 3 and4, the present embodiment is not limited to such an aspect.

Although the substrate contact SCN of the present embodiment and theabove-described respective First to Third Embodiments is used as asubstrate electrode for taking out a substrate potential from above, ithas a configuration in which a periphery of the substrate contactconductive layer CDL is surrounded by the insulating film II1(interlayer insulating film II1). For this reason, the substrate contactSCN has both of a function as the substrate electrode, and a function toelectrically separate the element from the other region in the same wayas the element isolation region DTR.

For this reason, by the configuration of the element formation region tobe surrounded by the substrate contact SCN as in the present embodiment,the element formation region can be electrically separated from theother region, and the substrate potential can be taken out.

In addition, since the substrate contact SCN has the function similar tothe element isolation region DTR, it becomes unnecessary to form theelement isolation region DTR as in the First Embodiment. In addition, inthe present embodiment, it becomes unnecessary to form anything in theregion where the substrate contact SCN in FIG. 1 is formed. For thisreason, constituent elements of the semiconductor chip CHP can bereduced, and the size of the semiconductor chip CHP can be reduced.

Hereinbefore, although the invention made by the present inventor hasbeen specifically explained on the basis of the embodiments, the presentinvention is not limited to the above-described embodiments, and it isneedless to say that various modifications are possible within the scopenot departing from the gist of the invention.

What is claimed is:
 1. A method for manufacturing a semiconductordevice, comprising the steps of: forming an element that has aconductive portion located on a main surface of a semiconductorsubstrate; forming a first concave portion that extends inside thesemiconductor substrate from the main surface; forming an insulatingfilm over the main surface, and over a side wall and a bottom wall ofthe first concave portion so as to cover the element and to form acapped hollow in the first concave portion; forming a first hole portionin the insulating film so as to reach the hollow in the first concaveportion from an upper surface of the insulating film, and to reach thesemiconductor substrate in the bottom wall of the first concave portionwhile leaving the insulating film over the side wall of the firstconcave portion; and forming a second hole portion that reaches theconductive portion from the upper surface of the insulating film,wherein the first and second hole portions are formed by the sameetching treatment.
 2. The method for manufacturing the semiconductordevice according to claim 1, further comprising the steps of: forming afirst conductive layer in the first hole portion so as to beelectrically coupled to the semiconductor substrate; and forming asecond conductive layer in the second hole portion so as to beelectrically coupled to the conductive portion, wherein the first andsecond conductive layers are formed by the same film-forming treatment.3. The method for manufacturing the semiconductor device according toclaim 2, wherein the first conductive layer is formed as a drainelectrode that is electrically coupled to a drain region of the element.4. The method for manufacturing the semiconductor device according toclaim 2, wherein the semiconductor substrate has first and secondelement formation regions that are located apart from each other, and afirst active barrier region that is located between the first and secondelement formation regions, the method further comprising the steps of:forming a first conductive-type first region in the semiconductorsubstrate so as to extend from the first element formation region atleast to the second element formation region through the active barrierregion; forming a second conductive-type second region on the mainsurface of the active barrier region so as to constitute p-n junctionwith a first conductive-type region including the first region; andforming a coupling conductive layer that is located over the mainsurface and electrically couples the first conductive layer to thesecond region, and wherein the first conductive layer is formed so as toreach the first region in the active barrier region.
 5. The method formanufacturing the semiconductor device according to claim 1, furthercomprising the steps of: forming a first conductive-type substrateregion in the semiconductor substrate; and forming a secondconductive-type buried region that is located closer to the main surfacethan the substrate region, wherein the first concave portion is formedso as to penetrate through the buried region to thereby reach thesubstrate region, and wherein the buried region is formed on an entiresurface of the semiconductor substrate in a plan view.
 6. The method formanufacturing the semiconductor device according to claim 1, furthercomprising the step of forming a second concave portion that extendsinside the semiconductor substrate from the main surface, wherein theinsulating film is formed over a side wall and a bottom wall of thesecond concave portion so as to form a capped hollow in the secondconcave portion, and wherein the first and second concave portions areformed by the same etching treatment.
 7. A semiconductor devicecomprising: a semiconductor substrate that has a main surface and has afirst concave portion formed so as to extend to an inside from the mainsurface; an element that has a conductive region located on the mainsurface of the semiconductor substrate; and an insulating film that isformed over the main surface so as to cover the element, is also formedover a side wall of the first concave portion in the first concaveportion, and thereby is formed so as to expose the semiconductorsubstrate in a bottom wall of the first concave portion, wherein thereis formed a first hole portion that reaches the bottom wall of the firstconcave portion through an inside of the first concave portion from anupper surface of the insulating film, and there is formed a second holeportion that reaches the conductive region from the upper surface of theinsulating film, the semiconductor device further comprising: a firstconductive layer formed in the first hole portion; and a secondconductive layer formed in the second hole portion, and wherein thefirst conductive layer and the second conductive layer include a samematerial.
 8. The semiconductor device according to claim 7, wherein thefirst conductive layer is formed as a drain electrode that iselectrically coupled to a drain region of the element.
 9. Thesemiconductor device according to claim 7, wherein the semiconductorsubstrate includes first and second element formation regions that arelocated apart from each other on the semiconductor substrate, and anactive barrier region that is located between the first and secondelement formation regions, the semiconductor device further comprising:a first conductive-type first region formed in the semiconductorsubstrate so as to extend from the first element formation region atleast to the second element formation region through the active barrierregion; a second conductive-type second region formed on the mainsurface of the active barrier region so as to constitute p-n junctionwith a first conductive-type region including the first region; and acoupling conductive layer that is located over the main surface andelectrically couples the first conductive layer to the second region,and wherein the first conductive layer is formed so as to reach thefirst region in the active barrier region.
 10. The semiconductor deviceaccording to claim 7, further comprising: a first conductive-typesubstrate region formed in the semiconductor substrate; and a secondconductive-type buried region that is formed in the semiconductorsubstrate and is located closer to the main surface than the substrateregion, wherein the first concave portion passes through the buriedregion to reach the substrate region, and wherein the buried region isformed on an entire surface of the semiconductor substrate in a planview.
 11. The semiconductor device according to claim 7, wherein asecond concave portion different from the first concave portion isformed in the main surface, and wherein the insulating film is formedover the main surface, and over a side wall and a bottom wall of thesecond concave portion so as to form a capped hollow in the secondconcave portion.